1. Field of the Invention
This invention relates generally to interface systems and, more specifically, to an interface system for use with a microprocessor based control system and a method therefor that provides a compact interface system particularly useful for interacting with a microprocessor based control system in an industrial environment or any other type of harsh operating environment.
2. Description of the Related Art
Prior art systems that permit a user to interface with a microprocessor based control system include push buttons, mouses, trackballs, touchscreens, keyboards, and joysticks. Each of these prior art interfacing systems have certain limitations. In particular, within the petroleum industry, the push button which is the simplest of these prior art interface systems has found the widest application in stand-alone tank monitors despite having several significant disadvantages. For example, as the complexity of the tank monitoring system increases, the number of push buttons required to accommodate all of the tank monitoring system functions also escalates. Consequently, as the quantity of required push buttons expands, the size of the stand-alone tank monitoring system increases, thereby raising the cost of the system. Furthermore, in the typically harsh industrial environment associated with the petroleum industry, push buttons suffer frequent failure when they are exposed to oil, dirt, and other debris. Push button interface systems are also somewhat user unfriendly. For example, in most sophisticated tank monitoring systems, there are a large number of potential functions such as tank level reporting, tank content reporting, and leak detection, and if there is a sizable number of tanks to be monitored, one skilled in the art will appreciate the complex and confusing push button sequences involved in selecting any one of the many possible functions for a tank.
In reference to the other prior art interface schemes, since keyboard interface systems are essentially an array of push buttons, it is not surprising that the shortcomings associated with the use of push button type interface systems in a stand-alone tank monitoring environment are also applicable to keyboard interface systems. Trackball, mouse, and joystick interface schemes rely on the unencumbered motion of a spherical surface over electromechanical transducers in order to drive electrical signals for moving a pointer on a visual display. The pointer is used to select an option from a menu of potential options. Again, the primary problem with these types of interface systems is that dirt, oil, and other debris associated with an industrial work site can collect on the working spherical surface, thereby causing malfunctioning of these systems. Touchscreen interface schemes also present significant drawbacks. For instance, when a user selects a displayed option by reaching out to touch the display screen, the view of the display console is at least partially inhibited. One skilled in the art will understand that in applications such as a tank monitoring system for use in an aircraft, covering the display console is not a prudent action. Moreover, in the petroleum industry and in other industrial applications of stand-alone tank monitoring systems, most users have dirt, oil, or other residue on their hands, therefore, when they touch the display screen to select an option, the debris from their hands is deposited on the screen, and consequently, over a period of time, the view of the screen becomes less clear.
Therefore, there existed a need to provide a rugged, compact, efficient, and user friendly interface system for use with a microprocessor based control system. This new interface system is particularly useful in stand-alone tank monitoring systems that may be found in petroleum manufacturing facilities, fuel stations, and aircraft. Moreover, this system is, in general, an excellent choice as an interface for other aircraft systems such as a navigational computer system due to the stability, space conservation, and flexibility of this new interface system. In addition, this interface system can be used in place of, or in addition to, keyboards, joysticks, mouses, trackballs, and touchscreens as a new type of interface for use with computers such as the personal computer.